I found this sub-adult bird in the early evening (long sunlight right now), and it was unable to fly - at least temporarily. It was resting on Crescent Beach just west of the Gurnet "Boathole". It tried to get to the water but the receding tide had left it high and dry and after a few clumsy flaps and flops it gave up - perhaps waiting for the tide to return so it could swim away. It seemed in good health and reasonably strong - no physical damage was apparent. When I returned the next day it was gone.